Development of axial skleton and muscles of the trunk Flashcards
When is the axial skeleton of the trunk formed?
During the 2nd month.
What is metamerism or metamery?
The repetition of alike elements
Segmentary organization, as somites.
When do somites disappear?
During the 5th week
Somites transform into other structures.
What is the sclerotome?
Portion of the somite-ventrally-derived mesenchymal cells.
Will give raise to bone structures.
When do somites decondensate and form the sclerotome?
During the 4rth week
What induces the conversion of somite to become sclerotome (mesenchymal cells)?
Induced by molecules (Sonic the hedgehog and noggin) produced by the notochord and the neural tube.
What will form the mesenchymall cells surrounding the notochord?
The body of the vertebrae.
Notochord, nucleus polpusus.
What will form the mesenchymall cells surrounding the nueral tube?
The vertebral arch.
Ossification of long and short bones?
Endochondral ossification
Mesenchymal cells —- Chondroblasts (cartilage) —- bone
When does the primary ossification begins?
Before the end of the 8th week.
What determines the shape/type of the vertebrae?
By Homeobox genes
From where is the sternum derived?
From the parietal layer* of the lateral mesoderm.
El que está más hacia a fuera.
What two regions can we find in the myotome, to what each derives?
Dorsomedial: intrinsic muscle of the back.
Ventrolateral: anterolateral body walls and limbs.
What do spinal nerves inervate?
The skeletal muscle and dermis.
From Somatic Nervous System
Which are the vertebrae that differ in number from the nerves?
The cervical part.
7 cervical vertebrae
8 cevical nerves.
